In many industries where a fluid is to be pumped from a well, sump or other body of fluid, such as a settling pond, the fluids contain particulate matter, and centrifugal-slurry pumps are commonly used to process such fluids to remove the fluid and solids from the well, sump or body of fluid. In many industries, such as the mining industry for example, the particulate solids are of a relatively smaller size and the slurry pump that is used in the application is particularly selected for its ability to process the type and size of solids that are entrained in the fluid as a result of the mining operations.
In other industries, however, the fluid to be pumped contains larger solids or debris that, when pumped using conventional slurry pump arrangements, will clog the impeller or other pump structures and will cause the pump to become damaged or to seize. One such example is in the processing of mature fine tailings (MFT) in which a mixture of water, clay, sand and residual hydrocarbons that are produced during mine extraction are pumped into settling ponds that can be quite massive, and possibly several kilometers in width. Such settling ponds are produced to allow heavier particulates, such as sand, to settle to the bottom while water settles at the top of the pond. It is desirable, if not required by law, to remove the MFT in order to return the land to its previous state after the mining operations have ended
It is frequently the case that settling ponds are established on lands that were formerly covered with vegetation, including large trees. Therefore, subsequent pumping of the MFT from settling ponds results in encountering large solids of vegetation (e.g., tree stumps and branches), as well as other objects that might have been discarded into the pond. Thus, the pumping of sand and larger solids from settling ponds is particularly challenging to many centrifugal pumps, and ultimately causes them to fail. The pumping operation must then be stopped and the pump, if submerged in the fluid, must be lifted out of the sump or well to allow for repair or replacement of the pump, all of which results in costly operational down-time and loss of equipment.
It would be beneficial, therefore, to provide a pumping assembly that is structured to process large solids and fluid-entrained debris into smaller sized matter before entering into the pump to avoid damaging the pump.